Mixed Conduction in an N-Type Organic Semiconductor in the Absence of Hydrophilic Side-Chains

Jokubas Surgailis, Achilleas Savva, Victor Druet, Bryan D. Paulsen, Ruiheng Wu, Amer Hamidi-Sakr, David Ohayon, Georgios Nikiforidis, Xingxing Chen, Iain McCulloch, Jonathan Rivnay, Sahika Inal

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Organic electrochemical transistors (OECTs) are the building blocks of biosensors, neuromorphic devices, and complementary circuits. One rule in the materials design for OECTs is the inclusion of a hydrophilic component in the chemical structure to enable ion transport in the film. Here, it is shown that the ladder-type, side-chain free polymer poly(benzimidazobenzophenanthroline) (BBL) performs significantly better in OECTs than the donor–acceptor type copolymer bearing hydrophilic ethylene glycol side chains (P-90). A combination of electrochemical techniques reveals that BBL exhibits a more efficient ion-to-electron coupling and higher OECT mobility than P-90. In situ atomic force microscopy scans evidence that BBL, which swells negligibly in electrolytes, undergoes a drastic and permanent change in morphology upon electrochemical doping. In contrast, P-90 substantially swells when immersed in electrolytes and shows moderate morphology changes induced by dopant ions. Ex situ grazing incidence wide-angle X-ray scattering suggests that the particular packing of BBL crystallites is minimally affected after doping, in contrast to P-90. BBL's ability to show exceptional mixed transport is due to the crystallites’ connectivity, which resists water uptake. This side chain-free route for the design of mixed conductors could bring the n-type OECT performance closer to the bar set by their p-type counterparts.
Original languageEnglish (US)
Pages (from-to)2010165
JournalAdvanced Functional Materials
DOIs
StatePublished - Mar 18 2021

ASJC Scopus subject areas

  • Biomaterials
  • Electrochemistry
  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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